It is known that asbestos yarns may be produced from asbestos dispersions in a continuous process, by disposing a plurality of nozzles fed with asbestos dispersion within a coagulating bath to form a plurality of individual strands. The individual strands are then combined, removed from the bath, and passed through a zone of low tension wherein the final stages of coagulation can take place; whereafter the thus combined strands are withdrawn as a single strand or yarn and collected, for example, by pot spinning, as described in U.S. Pat. No. 3,806,572.
In order to spin the combined coagulated asbestos strands produced by the aforementioned continuous process, the spinning unit as disclosed in the Italian Pat. No. 896,535 may be advantageously employed. The spinning unit therein described is a centrifugal cup-spinning spindle adapted to collect yarns wound in hollow-core bobbins, and comprises a cup having a neck from which it is suspended for rotation at a high speed about its axis. A tubular, vertically reciprocating distributing thread guide is mounted above the cup and passes through the neck into the cup. An axially stationary, pre-twisting tubular thread guide is positioned coaxially with the distributing thread guide between the latter and an overlying draft unit. The cup and thread guides are supported on a common member and may be mounted as a single unit on the spinning machine frame.
In the aforementioned process, the spindles or pot spinning devices continuously withdraw and collect the wet asbestos strands in a package. Periodically, the operation of the spindle must be interrupted, as for example, to remove a package of yarn when the pot has been filled to capacity. At the same time, it is inconvenient and impractical to interrupt the operation of the strand production unit, primarily due to the problem of the asbestos dispersion clogging in the nozzles. Heretofore, it was necessary for an operator to first manually sever the strand above the spindle and allow it to fall and collect to one side of the apparatus. Upon resumption of pot spinning, the operator would again have to sever the strand and reintroduce it into the inlet of the pot.
Since a large number of individual spindles are employed in a single production line, the foregoing manual operations require a great number of hands and are laborious and time consuming, especiallly since the strands are still wet and are continuously issuing from the coagulating bath. These problems are greatly aggravated, for example, when several spindles are stopped at the same time.
In order to overcome the above difficulties and to improve the efficiency of the spinning and overall operation, the present invention provides for a novel strand shearing and deflecting device to be associated with each one of the spinning units in the path of each asbestos strand to be spun, said device being located between the outlet of the strand production unit and the inlet of the associated spindle. Means are also provided to allow either selective or simultaneous operation of a plurality of such devices, so as to shear either one or several particular strands or all the strands flowing to their respective spinning units, and to deviate the sheared strands to a discharge, whenever the operation of one or more spindles is interrupted. When the spinning is again resumed, the strands are again severed and are redirected into their corresponding spindles.
The device of the present invention is particularly adapted for use with centrifugal pot spinning devices and is capable of handling any interruption in the spinning procedure. The device may be used in connection with all types of asbestos strands, as well as asbestos strands containing fillers or filamentary inserts made of metals, polymers or other materials.
The strand shearing and deflecting device of the invention particularly comprises a funnel element fixedly mounted on the spinning machine frame to guide the newly formed strand into the inlet of a spindle, and a slide mounted at the outlet end of the funnel and carrying on its underside a first straight pipe coaxial with the funnel and a second pipe having a bend therein. A double edge blade is mounted between the first and second pipes on the upper surface of the slide. The slide reciprocates underneath the funnel outlet between a spindle feeding position through the straight pipe and a strand deflecting position through the pipe having the angular bend. During movement of the slide between the two positions, the double edge blade severs the strand, and the severed end of the strand alternatively enters one of the pipe sections. The device thus allows for the deflection of the strand to and from the spindle, while severing the segment that is not collected when the spindle is stopped.
In addition, means are provided to supply a trickle or light flow of liquid down through the funnel during the strand shearing and deflecting procedure, in order to entrain and accompany the sheared strand, thus substituting for the tension ordinarily exerted on the strand by the pot spinning device. The tube of the funnel is sufficiently elongated to accommodate elastic rebound of the severed strand end, thereby preventing unthreading of the strand from the funnel.